μModule Regulators Shrink Power Supply Size and Design Effort

Introduction

When it comes to high density, efficient power supplies, switching regulators are a top choice, but what if a project lacks sufficient design resources to properly layout and test a switching power supply circuit? Like any other system, switching power supplies require component selection, derating, simulation, prototyping, board layout, analysis and design verification testing. Design engineers should focus on the guts of the new whiz-bang gadget, not the power supply to run it.

The LTM8020, LTM8022 and LTM8023 are three μModule regulators that require minimal design effort and only a few inexpensive passive components to make a complete power supply. The modules are small, accept a wide input operating range and can produce 0.2A, 1A and 2A, respectively.

Tiny, Self-Contained, 200mA Power Supply

The LTM8020 is small, with a package measuring only 6.25mm × 6.25mm × 2.32mm, but it accepts a wide 4V to 36V input voltage range, and can produce up to 1W for output voltages between 1.25V and 5V at 200mA. At light loads, Burst Mode operation keeps quiescent current to 50μA at no load. The current draw is less than 1μA when shut down. As seen in Figure 1, a complete LTM8020 power supply requires only an input capacitor, output capacitor and a single resistor to set the output voltage.

Figure 1. Generate 3.3V at 200mA with the LTM8020, two caps and a resistor.

Negative Power Supply with Few Components

Being a self-contained design, the LTM8020 can be easily configured to generate a negative voltage. Figure 2 shows an example of how to use the LTM8020 to generate –5V at 85mA from an input range of 4.5V to 30V. The part does not operate as a true buck converter in this configuration, so the maximum output current is less than that achievable in the buck configuration.

Figure 2. A simple reconfiguration of the μModule generates a negative output.

If You Need More Power…

The LTM8022 comes in a larger 11.25mm × 9mm × 2.82mm package than the LTM8020, but boasts a wider input range, 3.6V–36V, and output range, 0.8V–10V, for loads up to 1A. It also includes more control features, including a RUN/SS pin, synchronization, user adjustable switching frequency and a SHARE pin for paralleling modules. The LTM8022 also employs Burst Mode operation, drawing only 50μA quiescent current at no load while maintaining only 30mV of output voltage ripple. Like the LTM8020, the quiescent current when shut down is less than 1μA. The schematic is very simple, with examples of 3.3V and 8V output designs shown in Figures 3 and 4, respectively.

Figure 3. Produce 3.3V at 1A with LTM8022 and just four passive components.

Figure 4. The LTM8022 can produce 8V, too.

…Or, Even More Power…

The LTM8023 is the big brother of the LTM8022, capable of producing up to 2A of output current. The LTM8023 has the same input, output voltage range, and control features as the LTM8022. It also features Burst Mode operation and low quiescent current. The LTM8022 and LTM8023 share the same footprint and pin pattern, so even if you start a design with the LTM8022 but later find that you need more current, you can simply drop in the LTM8023. In most cases, the design will use identical passive components as the LTM8022, as seen in the 3.3V example in Figure 5.

Figure 5. The LTM8023 produces 3.3V at 2A with the same footprint and components required for the LTM8022 producing 1A.

Conclusion

The LTM8020, LTM8022 and LTM8023 μModule regulators make power supply development fast and easy. Their broad input and output voltage ranges, load capabilities and small size (see Table 1) make them readily fit into a wide variety of applications.

Table 1. Summary of LTM8000 series μModule regulators
Part Number VIN Range Max Load VOUT Range Size
LTM8020EV 4V to 36V 200mA 1.25V to 5V 6.25 × 6.25 × 2.32mm
LTM8022EV 3.6V to 36V 1A 0.8V to 10V 11.25 × 9 × 2.82mm
LTM8023EV 3.6V to 36V 2A 0.8V to 10V 11.25 × 9 × 2.82mm

Author

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David Ng